Optimized mechanism for paging transmission and reception

ABSTRACT

Methods and apparatus are provided for paging transmission and reception for UEs requiring coverage extension/coverage enhancement. In one novel aspect, the UE reports the CE status to the MME. CE level related information and the corresponding cell ID are provided from eNB to MME. MME sends paging information including the repetition number to all eNBs in the corresponding tracking area when paging the UE. In another novel aspect, a paging area is used for CE UEs. The UE receives paging area information, notifies the network, and updates the stored paging area information upon detecting changes between the received and the stored paging areas. In another embodiment, the UE reports its CE status upon detecting CE status changes. The eNB stores UE CE information and forwards it to neighboring eNBs in the same paging area. The eNB pages UEs on its CE UE list with repetition while paging other UEs normally.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is filed under 35 U.S.C. §111(a) and is based on andhereby claims priority under 35 U.S.C. §120 and §365(c) fromInternational Application No. PCT/CN2015/078557, with an internationalfiling date of May 8, 2015, which in turn claims priority from ChineseApplication Number CN201410195278.9, filed on May 9, 2014. Thisapplication is a continuation of International Application No.PCT/CN2015/078557, which claims priority from Chinese Application No.CN201410195278.9. International Application No. PCT/CN2015/078557 ispending as of the filing date of this application, and the United Statesis a designated state in International Application No.PCT/CN2015/078557. This application claims the benefit under 35 U.S.C.§119 from Chinese Application No. CN201410195278.9. The disclosure ofeach of the foregoing documents is incorporated herein by reference.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless communication,and, more particularly, to optimized mechanism for paging transmissionand reception.

BACKGROUND

Extending the reach of wireless communication is a challenge for alltypes of network, especially in the rural or remote areas. Due to thenature of the radio environment, services and power are difficult todeliver. It is both impractical and uneconomical to deliver coverageusing a traditional base station approach. Taking LTE for example, itwill be deployed at higher carrier frequencies than existing 2G and 3Gsystems, which implies higher propagation losses for LTE and potentiallya need to add more sites to ensure sufficiently good coverage. Addingsites is costly and requires lengthy negotiations. Machine-to-Machine(M2M) applications required low-cost devices and improved coverage otherthan the current cellular communication system. For example, some smartmetering deceives are often installed in the basements of residentialbuildings or locations shielded by foil-backed insulation, metalizedwindows, or traditional thick-walled building construction. These smartdevices suffer a significantly larger path-loss, such as 20 dB pathloss, than that in the typical operation condition of normal devices. Inorder to ensure the network provides the best possible solutions tomaximize coverage and serves the specific devices, the 3rd generationpartnership project (3GPP) RAN1 working group has studied for coverageimprovement for devices requiring coverage extension/coverageenhancement (CE). Some potential solutions have been identified such asrepetition of the physical channels to improve the coverage.

For network-originated data transfer to UEs requiring CE, somechallenges are expected when they are in RRC_IDLE, which include thenetwork does not know which cell the UE camps on, and whether the UErequires CE or not. Therefore, the network would not know whether topage the UE with CE through transmission repetitions. One possiblesolution is that on the network side, the MME assumes the UE does notrequire CE. The network pages the UE normally without requiring theknowledge of the UE CE status. However, under this approach since thereis no HARQ process for paging, the UE requiring CE normally cannotreceive the paging message in one paging occasion, which means the UE isunreachable.

Improvement and enhancement are required to efficiently paging the UEsrequiring CE in the wireless network.

SUMMARY

Methods and apparatus are provided for paging transmission and receptionfor UE requiring CE.

In one novel aspect, a paging area, which is a geographic area coveredby a subset of cells of a tracking area, is used for CE UEs. In oneembodiment, the paging area is identified by an identity (ID) or aneighboring cell list, which is acquired from the broadcast information.The UE receives the paging area information, and notifies the network ofits presence and updates the stored paging area information upondetecting any changes between the received paging area and a storedpaging area. In one embodiment, the UE establishes a RRC connection toindicate its presence. In another embodiment, the UE establishes a RRCconnection with establishment cause indicating a “paging area change.”In one embodiment, the UE receives the paging area information from thesystem information (SI). In another embodiment, the UE reports its CEstatus upon detecting changes of the CE status. In one embodiment, theUE reports its CE status periodically. In yet another embodiment, the UEreports its previously stored paging area information upon detectingchanges of paging area information between the received paging area andthe stored paging area.

In one novel aspect, the base station broadcasts its paging areainformation in the system information. The base station stores the UEinformation upon receiving presence indication from the UE requiring CEand forwards the information to neighboring base stations in the samepaging area. The base station pages UE on the CE UE list with repetitionand other UEs normally. In one embodiment, the base station releases theUE information from its CE UE list if one or more release triggeringevents are detected, including the UE is not successfully paged for anumber of tries or for a period, being informed by another group ofneighboring eNBs that the UE has moved out of the paging area.

In another novel aspect, the MME acquires CE status of a UE. The MMEdetermines a paging repetition number if the paged UE is in CE mode. TheMME notifies the one or more eNBs that the paging is for UEs of low costor requiring CE. In one embodiment, the MME provides a repetition numberto the base stations in the same tracking area such that the basestations send the paging messages repeatedly by the repetition number.In another embodiment, the MME receives CE related information from abase station. The CE related information includes the UE CE status andthe corresponding cell ID.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like numerals indicate like components,illustrate embodiments of the invention.

FIG. 1 illustrates an exemplary wireless communication network with UEsrequiring CE in accordance with embodiments of the current invention.

FIG. 2 illustrates an exemplary paging procedure between UE, eNB and MMEfor the paging procedure for the UE requiring CE in accordance withembodiments of the current invention.

FIG. 3 illustrates a wireless communication system with each paging areaorganized with one or more than one eNBs in accordance with embodimentsof the invention.

FIG. 4 illustrates an exemplary flow chart of for the UE to indicate toeNB its presence in the paging area in accordance with embodiments ofthe current invention.

FIG. 5 illustrates an exemplary flow chart for a UE to indicate to eNBthe change of the CE status in the paging area in accordance withembodiments of the current invention.

FIG. 6 illustrates an exemplary system level flow chart of the UE, theeNB and the MME for the paging procedure for UEs requiring CE inaccordance with embodiments of the current invention.

FIG. 7 illustrates an exemplary flow chart for the eNB to page the UErequiring CE in accordance with embodiments of the current invention.

FIG. 8 illustrates an exemplary flow diagram detailing procedures foreNBs in a paging area to store or update information of UEs requiring CEin accordance with embodiments of the current invention.

FIG. 9 shows an exemplary flow chart for the UE procedure of paging areahandling when in the CE mode in accordance with embodiments of thecurrent inventions.

FIG. 10 shows an exemplary flow chart for the base station procedure ofpaging area handling when in the CE mode in accordance with embodimentsof the current inventions.

FIG. 11 illustrates an exemplary diagram of a UE in the CE modereporting its CE status to the network in accordance with embodiments ofthe current invention.

FIG. 12 illustrates an exemplary paging procedure that the MME informsthe eNBs with CE status such that the paging message to the UE is sentrepeatedly in accordance with embodiments of the current invention.

FIG. 13 illustrates an exemplary diagram of the MME sending the CEstatus information to all eNBs in the tracking area such that the pagingmessages are sent repeatedly in accordance with embodiments of thecurrent invention.

FIG. 14 illustrates an exemplary flow chart of the UE requiring CEreporting its CE status to the network in accordance with embodiments ofthe current invention.

FIG. 15 illustrates of an exemplary flow chart of the eNB paging the UErequiring CE in accordance with embodiments of the current invention.

FIG. 16 illustrates of an exemplary flow chart of the MME sending UE CEstatus to the base stations in the tracking area in accordance withembodiments of the current invention.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 illustrates an exemplary wireless communication network 100 withUEs requiring CE in accordance with embodiments of the currentinvention. Wireless communication system 100 includes multiple fixedbase infrastructure units, such as base stations 111-116 and basestations 121-124, forming a network distributed over a geographicalregion, each base station covers a geographical area. The base unit mayalso be referred to as an access point, an access terminal, a basestation, a Node-B, an eNode-B, or by other terminology used in the art.The one or more base stations 111-116 and 121-124 serve a number ofmobile stations 101, 102 and 103 within a serving area, for example, acell, or within a cell sector. Backhaul connections, such as X2interface 131-136 connect the non-co-located base stations, such as111-116. These backhaul connections can be either ideal or non-ideal.

In one embodiment, mobile communication network 100 comprises aplurality of base stations eNBs and a plurality of mobile stations, suchas mobile stations 101, 102 and 103. UE 101 resides in the coverage areaof eNB 111 and communicates with eNB 111 through radio link 117. UE 101requires CE. The data blocks over link 117 needs to be repeatedlytransmitted so that UE 101 can receive the transmission correctly.Normal UEs 102 and 103 reside in the coverage areas of eNBs 116 and 121,respectively. UEs 102 and 103 communicate with eNBs 116 and 121 throughradio links 118 and 125, respectively. When there is a downlink packetto be sent from the eNB to the mobile station, each mobile station getsa downlink assignment, e.g., a set of radio resources in a physicaldownlink shared channel (PDSCH). When a UE needs to send a packet toeNodeB in the uplink, the mobile station gets a grant from the eNodeBthat assigns a physical downlink uplink shared channel (PUSCH)consisting of a set of uplink radio resources. The mobile station getsthe downlink or uplink scheduling information from a physical downlinkcontrol channel (PDCCH) or an enhanced physical downlink control channel(EPDCCH) that is targeted specifically to that mobile station. Thedownlink or uplink scheduling information and the other controlinformation, carried by PDCCH, is referred to as downlink controlinformation (DCI).

A network entity, such as a mobility management entity (MME) 141 isconnected with base stations such as eNB 111-116 and 121-124, viaexemplary links such as 137-139. Though not shown the drawings, each eNBof wireless network 100 may have a link with MME 141. In wirelessnetwork 100, paging procedures are initiated by a network entity such asMME 141. One or more cells or eNBs form a tracking area. For example, atracking area 110 is formed including eNBs 111 to 116 or cells served byeNBs 111 to 116. A tracking area 120 includes eNBs 121 to 124 or cellsserved by eNBs 121 to 124. While UEs are in the idle mode, the locationsof UEs are known by MME, at the track area level. When the network needsto page a UE, the MME sends the paging message to all the eNBs in thetracking area where the UE resides. For example, MME 141 sends thepaging message to all eNBs in tracking area 110 when it needs to pageidle-mode UE 101 or idle-mode UE 102. Similarly, when paging idle-modeUE 103, MME 141 sends paging message to all eNBs in tracking area 120.

In one example, UE 101 requires CE, which means data blocks needs to betransmitted repeated so that UE 101 can receive them correctly.Therefore, paging message to idle-mode UE 101 needs to be repeatedlytransmitted over different subframes by a repetition. In doing so, eNBs111-116 all need to transmit the paging messages repeatedly by therepetition number. Large amount of data traffic in tracking area 110 isgenerated. In one novel aspect, paging areas formed, each consists of asubset of eNBs or cells of a tracking area. Each eNB keeps track of theUEs requiring CE in the paging area. eNBs in the same paging areaexchanges CE UE information via the X2 interface. UEs requiring CEreports its CE status to the serving cell.

In one embodiment, the communication system utilizes RRC layer tocontrol communications between a UE and an eNB at the radio interfaceand the mobility of a UE crossing cells. RRC layer performs systeminformation broadcasting/reception, paging, RRC connectionestablishment/release, NAS information transfer, mobility control and soon. Exemplary of RRC layer includes the developing Long Term Evolution(LTE) of the 3GPP UMTS standard.

In another embodiment, the communication system utilizes NAS layer tocontrol communications between a UE and MME. NAS layer performs EPSbearer management, authentication, ECM-IDLE mobility handling, pagingorigination in ECM-IDLE and security control. Exemplary of NAS layerincludes the developing Long Term Evolution (LTE) of the 3GPP UMTSstandard.

FIG. 1 further shows simplified block diagrams 160, 150 and 170 formobile station 101, and base station 111 and MME 141, respectively, inaccordance with the current invention.

The eNB 111 has an antenna 155, which transmits and receives radiosignals. A RF transceiver module 153, coupled with the antenna, receivesRF signals from antenna 155, converts them to baseband signals, andsends them to processor 152. RF transceiver 153 also converts receivedbaseband signals from processor 152, converts them to RF signals, andsends out to antenna 155. Processor 152 processes the received basebandsignals and invokes different functional modules to perform features ineNB 111. Memory 151 stores program instructions and data 154 to controlthe operations of eNB 111. eNB 111 also includes a set of controlmodules, such as a paging area handler 156, a UE CE status handler 157and paging module 158, to carry out functional tasks and page mobilestations. Paging area handler 156 are functions and communicates witheNB and UE to implement the paging area methods. In another case, if thepaging area is not formed, so the paging with repetition could beimplemented, so in this case, the paging area handler 156 could beomitted, and paging module 158 could be used to page UE to implement thepaging without paging area information, for example, the paging UE withrepetition, or normally paging without repetition. UE CE status handler157 performs tasks such the network entity can acquire CE status of UEs.

Mobile station 101 has an antenna 165, which transmits and receivesradio signals. A RF transceiver module 163, coupled with the antenna,receives RF signals from antenna 165, converts them to baseband signals,and sends them to processor 162. RF transceiver 163 also convertsreceived baseband signals from processor 162, converts them to RFsignals, and sends out to antenna 165. Processor 162 processes thereceived baseband signals and invokes different functional modules toperform features in mobile station 101. Memory 161 stores programinstructions and data 166 to control the operations of mobile station101.

Mobile station 101 also includes a set of control modules that carry outfunctional tasks. An information handler 191 stores information of apaging, e.g. the paging message. The paging area is a subset of atracking area for a paging message. A paging area handler 192 receivesinformation of a paging area from a base station in a wireless networkwhen the UE requires CE, determines if there is any change between thepaging area and the stored paging area of the UE, and notifies the basestation if there is any paging area change. A paging module 193 receivesand processes paging messages in the paging area, wherein the pagemessages are transmitted repeatedly by a repetition number. In anotherembodiment, the paging area is not formed, so the paging area handler192 could be omitted, and the paging module 193 receives and processespaging messages, wherein a repetition number transmits the pagingmessages repeatedly. A CE status handler 194 detects UE CE status andforwards the status to the network entity.

MME 141 has a transceiver module 173 that receives messages, and sendsthem to processor 172. Transceiver 173 also converts received signalsfrom processor 172 and sends the signals to other entities. Processor172 processes the received signals and invokes different functionalmodules to perform features in MME 141. Memory 171 stores programinstructions and data 174 to control the operations of MME 141. MME 141also includes control modules, such as CE status handler 177, to carryout the function and tasks for MME 141, and paging module 178 to carryout the function and tasks for paging the UE in the tracking area.

FIG. 2 illustrates an exemplary paging procedure between UE, eNB, andMME for the paging procedure for the UE requiring CE in accordance withembodiments of the current invention. UE 201 requires CE. UE 201 in idlemode resides in the tracking area served by eNBs 202, 203, and 204,which are connected with a network entity, such as MME 205 via S1interface. From the network side, if there is a terminating call towardsa UE in RRC_IDLE, the MME initiates the paging procedure by sendingPAGING message to each eNB with cells belonging to the tracking area(s)in which the UE is registered over the S1 interface using the SIapplication protocol (S1AP). Paging requests are sent to the relevanteNBs according to the mobility information kept in the UE's MME contextin the serving MME. At steps 211, 212 and 213, MME 205 sends pagingrequests to eNBs 204, 203 and 202, respectively. The paging responseback to the MME is initiated on NAS layer and is sent by the eNBs basedon NAS-level routing information. Upon receiving the paging message fromthe MME, the eNB belonging to the tracking area indicated in the S1APpaging message performs paging of the UE over the radio interface bysending paging message on the cells. For UEs requiring CE, such as UE201, paging-related information transmission over physical channels(PDSCH and possibly PDCCH) may need repetitions across multiplesubframes. At steps 231 to 233, eNBs 204, 203, and 202 send pagingmessages to UE 201 with repetitions, respectively.

In order to save the radio resources of paging with repetitions, whichoccurs in the whole tracking area, smaller geographic area than thetracking area is defined in the embodiments of this invention. If theUEs requiring CE are largely stationary, it is assumed that those UEsstay in the area in a relatively long period of time. Also for themachine type communication (MTC) UE with low mobility status orstationary, such assumption is also applicable. A geographic area calledpaging area is used for paging the UEs requiring CE with low mobilitystatus or being stationary. The paging area is covered by one or moreeNBs, which are in the neighborhood and communicated with each otherthrough X2 interface. Although the paging message is generated from MME,who pages the UE in all the cells of the tracking area, only the cellsbelonging to the paging area where the UE requiring CE is present needsto transmit the paging message with repetitions for coverageenhancement. For example, eNBs 202 and 204 form the paging area and UE201 resides in the paging area. In one novel aspect, only eNBs 202 and204 pages UE 201 with the same repetition number or a differentrepetition number. eNB 203 upon receiving the paging request from MME205, pages UE 201 without repetition. In one embodiment, the same numberof paging repetitions is applied in all the cells belonging to thepaging area for one specific UE requiring CE. The repetition number isdetermined at least based on the coverage status of the paged UE.

FIG. 3 illustrates a wireless communication system with each paging areaorganized with one or more than one eNBs in accordance with embodimentsof the invention. A tracking area 110 served by MME 141 as shown in FIG.3, the same as shown in FIG. 1, includes eNBs 111 to 116, each covers ageographical area. In one novel aspect, multiple paging areas are formedeach includes a subset of eNBs in the tracking area. For example, eNBs111 and 112 provide coverage distributed over a geographical region,which is paging area 310. eNB 113 forms a paging area 320. eNBs 114, 115and 116 provide coverage distributed over a geographical region, whichis paging area 330. The paging area 310 is formed through thecoordination between eNB 111 and eNB 112 over X2 interface 131. Thepaging area 330 is formed through the coordination between eNBs 114,115, and 116 over X2 interface 134, 135, and 136.

Since the paging area is covered by a group of cells, it can beidentified by a cell lists. For E-UTRAN, each entry of the cell listscorresponds to the E-UTRAN Cell Global Identifier (ECGI) and PhysicalCell Identifier (PCI) of the cell. Alternatively, the paging area can beidentified by a paging area identity. For example, different paging areawill have a different identity, which can be identified uniquely over awide area. In order to make the UEs requiring CE know which paging areathe cell where it camps on, the paging-area related information, such ascell lists or paging area identity, needs to be broadcast in the systeminformation. Each eNB can contain cells belonging to different pagingareas, whereas each cell can only belong to one paging area.

The paging area information is derived through coordination between theneighboring eNBs under the management of the MME. The paging area isidentified by an identity or a neighboring cell list. eNBs which providecoverage to the same paging area should have the same paging areaidentity or the same neighboring cell list. The paging area informationis broadcast by eNBs.

eNBs in the paging area consider the UE is a new corner if no UEinformation for the UE requiring CE has been stored by them. UE 301 inidle mode camps on the cell of eNB 111 for the first time. In this case,if the CE indication from UE 301 is received, eNB 111 shares thisinformation with eNB 112 in the same paging area. Since each eNBs sharesthe UE information with the neighboring eNBs, the UE information for aspecific UE requiring CE is kept by all the eNBs in the paging area,even if the RRC connection of the UE is released. The UE information forthe UE requiring CE, which is shared by the eNBs in the paging area,includes UE identity as well as the CE status. When UE 301 moves to anew location served by eNB 113, denoted by UE 301-M, the UE notifies eNB113 of its presence upon detecting different paging area through thebroadcasted system information. Similarly, eNB 113 would shareinformation of UE 301-M with eNBs in the same paging area. In thisexample, there is no other eNBs in the same paging area as eNB 113.

FIG. 4 illustrates an exemplary flow chart of for the UE to indicate toeNB its presence in the paging area in accordance with embodiments ofthe current invention. At step 401, the UE enters RRC_IDLE mode.Subsequently, at step 401, the UE performs cell selection or reselectionto find a cell to camp on. In one embodiment, if UE determines that itrequires CE, the UE determines if the cell it detects supports CE. Inone embodiment, the UE prefers cells that support CE. In anotherembodiment, the UE only selects cells that support CE. At step 403, theUE camps on a cell that supports CE. At step 404, the UE acquires thepaging area information from the system information. At step 411, the UEchecks a stored paging area information exists. If UE has not stored anypaging area information, i.e. there is no current value for the pagingarea, the UE moves to step 421. At step 421, the UE establishes RRCconnection with the network. Subsequently, at step 422, the UE indicatesits presence in the paging area to the network. Then the correspondinginformation of the paging area e.g. paging area identity or theneighboring cell list is stored by the UE at step 424. If at step 411,the UE determines that there is paging area information stored, it movesto step 412. At step 412, the UE determines that the received pagingarea is different from the stored paging area. If step 412 determinesthat there is no difference in the paging area, the UE moves to step 430and ends the paging area updating procedure, and in one case, toestablish a RRC connection with the original network as usual (notshown). If step 412 determines that there exists any difference betweenthe received paging area and the stored paging area, the UE moves tostep 421 and establishes a RRC connection with the network. When UEperforms cell selection/reselection and camps on another cell, UE checkswhether it moves into a different paging area. If UE moves to adifferent paging area, it establishes a RRC connection with the networkand indicates its presence in the new paging area to the network.Subsequently, at step 422, the UE indicates its presence in the pagingarea to the network. In one embodiment, the UE optionally sends itspreviously stored paging area information to the new base station (step423). In another embodiment, the corresponding information of the pagingarea e.g. paging area identity or the neighboring cell list is updatedby the UE at step 424. Even if the RRC connection with the network isreleased, both the UE and the base stations keep the paging areainformation. The UE in RRC_IDLE can check whether it moves to adifferent paging area due to IDLE mode mobility by acquiring paging areainformation.

The CE status of the UE changes with UE mobility or due to other factorssuch as environmental changes. In one embodiment, the CE statusindicates only CE-UE or non-CE-UE. In another embodiment, differentlevels for a CE status are used. In either cases, the UE monitors its CEstatus, updates CE changes to the network accordingly.

FIG. 5 illustrates an exemplary flow chart for a UE to indicate to eNBthe change of the CE status in the paging area in accordance withembodiments of the current invention. At step 511, a UE 501 camps on acell served by an eNB 502. eNB 502, together with eNBs 503 and 504, forma paging area 505. UE 501 monitors the CE status at step 512. At step513, upon detecting change of the coverage status of the UE, UE 501updates its coverage status to the network. If UE 501 is inRRC_CONNECTED, UE 501 reports its coverage status directly. Otherwise,UE 501 establishes a RRC connection with the network for the purpose ofcoverage status update. In one embodiment, at step 521, UE 501 sends CEstatus change indication to eNB 502. Upon receiving the CE status changeindication from UE 501, eNB 502 updates the information with itsneighboring eNBs in the same paging area 505. At step 522, eNB 502 sendsCE status change indication of UE 501 to eNB 503. At step 523, eNB 502sends CE status change indication of UE 501 to eNB 504. The above steps522 and 523 perform either in parallel or in sequence. In anotherembodiment, UE 501 reports its CE status periodically to the eNB. In oneembodiment, such periodic report can be aligned with other UE periodicreports.

FIG. 6 illustrates an exemplary system level flow chart of the UE, theeNB and the MME for the paging procedure for UEs requiring CE inaccordance with embodiments of the current invention. A UE 601 camps onan eNB 602. UE 601 requires CE. A paging area 605 includes eNBs 602, 603and 604. eNBs 602, 603 and 604 communicates with an MME 606. FIG. 6includes a paging-area update procedure 610 including steps 611 to 613,a paging procedure 620 including steps 621 to 623, and a releasingprocedure 630 including steps 631 to 633.

At step 611, UE 601 indicates its presence, with CE status, to eNB 602.eNB 602 stores UE 601 information to its CE UE list at step 612. eNB 602shares UE 601 information with eNB 603 and 604 in the same paging area605 at step 613.

At step 621, MME 606 sends paging request for UE 601 to all eNBs in thetracking area. At step 622, eNB 602 checks if UE 601 requires CE. If yesin step 622, at step 623, eNB 602 pages UE 601 repeatedly by arepetition number. If no, eNB 602 pages UE 601 normally. Similarly, eNBs603 and 604 in paging area 605 page UE 601 repeatedly by the repetitionnumber because they determine that UE 601 requires CE. Or else eNBs 603and 604 in paging area 605 page UE 601 normally, i.e. withoutrepetition.

The UE information for the specific UE requiring CE may be released bythe eNBs belonging to the paging area under certain conditions, such asthe coverage status of the UE becomes better and changes to normal mode,or the UE requiring CE is not successfully paged in a pre-defined numberof tries, or eNBs in another paging area informs that the UE is out ofthe original paging area. At step 631, eNB 602 detects one or morerelease UE information triggers/conditions for UE 601. At step 632, eNB602 releases UE 601 from its CE UE list. At step 633, eNB 602 informseNBs 603 and 604 of the releasing of UE 601.

In one novel aspect, the enhancement for the paging procedure for CE UEsrequires no changes at the MME level. The eNBs keeps track of UEsrequiring CE and pages UEs differently based on their CE status. FIG. 7illustrates an exemplary flow chart for the eNB to page the UE requiringCE in accordance with embodiments of the current invention. At step 701,the eNB receives paging request from the MME. The eNB, at step 710, theeNB checks the stored UE information based on the paged UE ID. At step702, the eNB checks if the paged UE is a UE requiring CE, i.e., if thepaged UE is a CE UE in the paging area. If step 702 determines no, theeNB pages the UE normally without repetition. If step 702 determinesyes, the eNB pages the UE repeatedly by a repetition number.

FIG. 8 illustrates an exemplary flow diagram detailing procedures foreNBs in a paging area to store or update information of UEs requiring CEin accordance with embodiments of the current invention. FIG. 8 includesa UE procedure 810 and an eNB procedure 830. UE 801 requires CE. At step811, UE 801 camps on eNB 802 and acquires the paging area information.eNB 802, together with eNBs 803 and 804 form a paging area 805. At step810, UE 801 checks stored coverage area information. At step 812, UE 801determines if there is paging area changes between the receiving pagingarea from eNB 802 and the stored paging area information. UE 801determines a paging area change if there was no previous stored pagingarea information or the received paging area is different from thestored paging area. Upon detecting paging area changes, UE 801 moves tostep 821 and sends an RRCConnection Request message to eNB 802. At step822, UE 802 receives an RRCConnection Setup message from eNB 802. Atstep 823, UE 801 sends an RRCConnection Complete message to eNB 802. Inone embodiment, UE 801 includes the CE status indication or informationin the RRCConnectionComplete or RRCConnectionRequest message. In anotherembodiment, the UE establishes a RRC connection with establishment causeindicating a “paging area change.” At step 831, eNB 802 upon receivingCE status information in the RRCConnectionComplete orRRCConnectionRequest message, stores the UE information in its CE UElist. In one embodiment, the UE information includes the UE ID and theCE status. At step 832, eNB 802 forwards the UE information to eNB 803.At step 833, eNB 803 stores the UE information in its CE UE list. Atstep 834, eNB 802 forwards the UE information to eNB 804. At step 835,UE 804 stores the UE information in its CE UE list.

FIG. 9 shows an exemplary flow chart for the UE procedure of paging areahandling when in the CE mode in accordance with embodiments of thecurrent inventions. At step 901, the UE requiring a CE receivesinformation of a paging area from a base station in a wireless network,wherein the paging area is a subset of a tracking area for. At step 902,the UE determines if there is any change between the received pagingarea and a stored paging area of the UE. At step 903, the UE notifiesthe base station if there is any paging area change. At step 904, the UEreceives paging messages in the paging area, wherein the paging messagesare transmitted repeatedly by a repetition number.

FIG. 10 shows an exemplary flow chart for the base station procedure ofpaging area handling when in the CE mode in accordance with embodimentsof the current inventions. At step 1001, the base station storesinformation of a paging area, wherein the paging area is a geographicarea covered by a cluster of neighboring base stations. At step 1002,the base station stores a CE (CE) UE list comprising UEs requiring CE.At step 1003, the base station updates the CE UE list upon detectingtriggering event. At step 1004, the base station pages the UEs on the CEUE list repeatedly by a repetition number.

Using paging area solutions, the wireless network can page the UEs in CEmode efficiently. Such solution requires system level modifications andadditional signaling procedures. Another possible solution is to requirethe UE to report the CE status to the network entity, such as the MMEthrough eNB. When the MME needs to page the UE, it will inform all theeNBs in the corresponding tracking area to page the UE with repetitions.This simplified solution, though less efficient, would require lesssignaling.

FIG. 11 illustrates an exemplary diagram of a UE in the CE modereporting its CE status to the network in accordance with embodiments ofthe current invention. At step 1111, a UE 1101 camps on a cell served byan eNB 1102. eNB 1102 communicates with a network control entity, suchas an MME 1103. UE 1101 monitors the CE status at step 1112. In oneembodiment, UE 1101 determines its being in the CE mode if the UE is alow cost UE. UE 1101 also determines its being in the CE mode if thenormal UE requires CE. At step 1121, the UE upon detecting CE mode,sends the CE status report to eNB 1102. If UE 1101 is in RRC_CONNECTED,UE 1101 reports its coverage status directly. Otherwise, UE 1101establishes a RRC connection with the network for the purpose ofcoverage status report. Upon receiving the CE status report from UE1101, eNB 1102 sends the CE status report to MME 1103. In oneembodiment, UE 1101 reports its CE status upon entering a new trackingarea. In one embodiment, the CE status report from the UE includes a CEstatus of the UE and a corresponding cell ID for the UE. The eNB relaysthe UE CE status report directly to the MME. In another embodiment, theCE status report from the UE includes the CE status of the UE only. TheeNB adds corresponding cell information in its CE status report andsends the CE status of the UE and the corresponding cell ID for the UEto MME.

FIG. 12 illustrates an exemplary paging procedure that the MME informsthe eNBs with CE status such that the paging message to the UE is sentrepeatedly in accordance with embodiments of the current invention. UE1201 requires CE. UE 1201 in idle mode resides in a tracking area 1206served by eNBs 1202, 1203, and 1204, which are connected with a networkentity, such as MME 1205 via S1 interface. In one embodiment, MME 1205determines the CE status of UE 1201. Upon detecting that UE 1201requires CE, MME 1205 sends information to all base stations in trackingarea 1206. At steps 1211, 1212 and 1213, MME 205 sends paging requeststo eNBs 1204, 1203 and 1202, respectively. The paging response back tothe MME is initiated on NAS layer and is sent by the eNBs based onNAS-level routing information. Upon receiving the paging message fromthe MME, the eNB belonging to the tracking area indicated in the S1APpaging message performs paging of the UE over the radio interface bysending paging message on the cells repeatedly. In one embodiment, upondetecting CE information in the S1AP paging message indicating CE isrequired for the paged UE, the base stations in tracking area 1206 sendpage messages to UE 1201 repeatedly by a repetition. eNBs 1204, 1203 and1202 send paging messages to UE 1201 repeatedly at steps 1231, 1232 and1233, respectively. In one embodiment, the repetition number is providedto the base stations by the MME.

FIG. 13 illustrates an exemplary diagram of the MME sending the CEstatus information to all eNBs in the tracking area such that the pagingmessages are sent repeatedly in accordance with embodiments of thecurrent invention. A tracking area 110 served by MME 141, as shown inFIG. 1, includes eNBs 111 to 116, each covers a geographical area. A UE1301, requiring CE, camps on eNB 116. MME 141 acquires the CE status ofUE 1301. In one embodiment, MME 141 stores CE status information of UE1301. Upon a mobile terminating call being initiated to UE 1301, MME 141sends paging requests to all eNBs in tracking area 110. In one novelaspect, MME 141 sends the paging request to all base stations intracking area 110 and indicates CE information of the paged UE. Uponreceiving the paging request with CE information from MME 141, eNBs 111to 116 pages UE 1301 repeatedly by a repetition number. In oneembodiment, the repetition number is provided by MME 141. In oneembodiment, the repetition number is included in the paging requestmessage. In another embodiment, the eNBs derives its own repetitionnumber based on the information from the MME. In yet another embodiment,the repetition number is based on the CE status.

FIG. 14 illustrates an exemplary flow chart of the UE requiring CEreporting its CE status to the network in accordance with embodiments ofthe current invention. At step 1401, the UE detects a CE mode in awireless network. At step 1402, the UE sends a CE report indicating theCE mode to the network. At step 1403, the UE receives a paging messagefrom the network, wherein the paging message is transmitted repeatedlyby a repetition number.

FIG. 15 illustrates of an exemplary flow chart of the eNB paging the UErequiring CE in accordance with embodiments of the current invention. Atstep 1501, the base station receives a paging request for a UE in a CEmode from a network entity in a wireless network. At step 1502, the basestation sends a paging message repeatedly by a repetition number to theUE.

FIG. 16 illustrates of an exemplary flow chart of the MME sending UE CEstatus to the base stations in the tracking area in accordance withembodiments of the current invention. At step 1601, the network entitydetermines a CE mode for a UE in a wireless network. At step 1602, thenetwork entity sends a paging request for the UE to one or more basestations in a tracking area of the UE, wherein the paging requestindicates the CE mode for the UE.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. Accordingly, various modifications,adaptations, and combinations of various features of the describedembodiments can be practiced without departing from the scope of theinvention as set forth in the claims.

What is claimed is:
 1. A method comprising: receiving information of apaging area by a user equipment (UE) requiring a coverageextension/coverage enhancement (CE) from a base station in a wirelessnetwork, wherein the paging area is a subset of a tracking area coveredby a subset of one or more base stations or cells which are closest tothe UE; determining if there is one or more changes between the receivedpaging area and a stored paging area of the UE; notifying the basestation if there is one or more paging area changes; and receivingpaging messages in the paging area, wherein each paging messages for theUE is transmitted repeatedly by a repetition number greater than one. 2.The method of claim 1, wherein the notifying the base station involves:establishing a radio resource control (RRC) connection with the basestation; and reporting a CE status of the UE to the base station.
 3. Themethod of claim 2, wherein an establishment cause IE of a RRC ConnectionRequest for the RRC connection establishment indicating a paging areachange.
 4. The method of claim 2 further comprising: reporting thestored paging area information to the base station.
 5. The method ofclaim 1 further comprising: updating the stored paging area if there ispaging area change.
 6. The method of claim 1 further comprising:reporting the stored paging area information to the wireless networkperiodically.
 7. The method of claim 1 further comprising: detecting aCE status change; and reporting the CE status change to the wirelessnetwork.
 8. A method comprising: storing information of a paging area bya base station, wherein the paging area is a geographic area covered bya cluster of neighboring base station, and wherein the paging area is asubset of a tracking area covered by a subset of one or more basestations or cells which are closest to one or more corresponding UEs;storing a coverage extension/coverage enhancement (CE) user equipment(UE) list comprising UEs requiring CE, wherein repetition transmissionfor each transmission is used for UEs requiring CE; updating the CE UElist upon detecting triggering event; and paging the UEs on the CE UElist repeatedly by a repetition number greater than one.
 9. The methodof claim 8, wherein the paging area is derived by coordinating amongneighboring base stations identified by a base station ID or aneighboring cell list.
 10. The method of claim 8 further comprising:broadcasting the information of the paging area in a system informationmessage.
 11. The method claim 8 wherein the triggering event isreceiving a notification of presence by a UE requiring CE.
 12. Themethod of claim 11 wherein the notification of presence includes a CEstatus of the UE.
 13. The method of claim 11 further comprising:establishing a radio resource control (RRC) connection with the UE, andwherein an establishment cause IE in a RRC Connection Request messagefor the RRC establishment indicates a paging area change.
 14. The methodof claim 11 further comprising: forwarding the UE notification ofpresence information to the base stations in the paging area.
 15. Themethod of claim 8, wherein the triggering event is receiving anotification of CE UE presence from a neighboring base station.
 16. Themethod of claim 8 further comprising: deleting one or more UEs from theCE UE list upon detecting one or more releasing events.
 17. The methodof claim 16 wherein the release events comprising: failure to receive apaging response from the UE after repeatedly tries by the repetitionnumber, failure to receive a paging response after a period of time, orreceiving a notification from a neighboring base station indicating theUE is out of the paging area.
 18. A user equipment (UE) comprising atransceiver that transmits and receives radio signals via a first radioaccess link; an information storage circuit that stores information of astored paging area; a paging area tracker circuit that receivesinformation of a paging area from a base station when the UE requirescoverage extension/coverage enhancement (CE), wherein the paging area iscovered by a subset of one or more base stations or cells which areclosest to the UE, determines if there is one or more changes betweenthe paging area and the stored paging area of the UE, and notifies thebase station if there is one or more paging area changes; and a pagercircuit that receives and processes paging messages in the paging area,wherein the page messages are transmitted repeatedly by a repetitionnumber greater than one.
 19. The UE of claim 18, wherein the paging areatracker circuit establishes a radio resource control (RRC) connectionwith the base station and reports a CE status of the UE to the basestation.
 20. The UE claim 19, wherein an establishment cause IE of a RRCConnection Request for the RRC connection establishment indicates apaging area change.
 21. The UE of claim 19, wherein the paging areatracker circuit further reports the stored paging area information tothe wireless network.
 22. The UE of claim 18, wherein the informationstorage circuit updates the stored paging area if there is paging areachange.
 23. The UE of claim 18, wherein the paging area tracker circuitreports the stored paging area information to the wireless networkperiodically.
 24. The UE of claim 18, wherein the paging area trackercircuit reports CE status to the wireless network upon detecting a CEstatus change.